This is what I came in to post. The PBS series “The Secret Life of the Brain” devoted most of an episode to this.
By no stretch of the imagination am I an expert on this, but this is what I can gather based on my memory of undergrad psych units and some bashing through google:
Originally posted by Mr Excellent:
This seems to be jumbling up corpus callostomies, hemispherectomies and functional hemispherectomies.
A corpus callostomy involves the severing of the corpus callosum, which is the connective tissue between the left and right hemispheres of the brain. Severing these fibres cuts all ties between the cerebral hemispheres, and as such one of its uses is to localise seizures to one half of the brain. This causes a condition known as split brain, which I think is absolutely fascinating and well worth delving further into if you have the time and inclination.
An anatomical hemispherectomy on the other hand involves the removal of a large portion of one of the cerebral hemispheres. This is rarely done anymore, and even when it is preformed it is done mainly in young children whose brains have enough plasticity to be able to rearrange themselves to allow the remaining tissue to take over the functions usually found in the lost areas (as mentioned by Der Trihs). Furthermore, it is only done when the half of the brain to be removed is non or minimally functional to begin with. A functional hemispherectomy (which is also described somewhat in the links for anatomical hemispherectomy) is used as a less extreme route than the anatomical hemispherectomy and involves (from here):
So to address the OP, yes it is possible for people to live with half a brain (given that the half removed doesn’t include the most vital brain regions such as those found in the brainstem, midbrain etc.) however the quality of life they have after such a procedure would probably depend on a number of factors, including but not limited to their age at the time of the operation. Also, although it is possible for us to live with half a brain, it is rarely necessary for such an extreme measure to be taken anymore.
And come to think of it I’m pretty sure Grey’s Anatomy once featured a hemispherectomy on a little girl… not that it’s relevant at all, just thought I’d through it out there.
That is absolutely amazing!
Getting back to all those brain anomalies (half brain, hollow brain etc). Doesn’t it lead to the question, how much brain do we need? These people seem to be functioning quite well with half the brain cells that I have (assuming my brain isn’t hollow).
A friend of mine suggested that evolution doesn’t always makes sense meaning that big brains don’t actually make us smart but that we just happened to be evolved from big brain ancestors.
This doesn’t make sense because a big brain is an evolutionary disadvantage in childbirth.
In other words, if we could live with brain that is half the size then why didn’t we evolved that way?
While a search isn’t throwing anything up, there is an old thread where we pointed out that that article significantly overstates the reality of such cases. (Since it’s by Richard “Forbidden Science” Milton, that’s perhaps no great surprise.) There are alternative explanations along the lines of that, while the pressure has produced a greatly compressed and distorted brain, they may well still have much the normal complement of neurons. An amazing example of how plastic brain development can be, but hardly an example of someone with “half a brain”, much less virtually none at all.
For example, this blog entry criticises some of Lorber’s claims.